코다파 간섭 기법을 이용한 콘크리트의 음향탄성효과 분석

Abstract

Velocity of elastic wave propagated from solids can be changed by the stress condition of it, so if Radio velocity of elastic wave is measured, stress condition changes of solids will be revealed from it. This stress dependency of elastic wave can be defined theoretically, and the study for utilizing this on stress condition measurement for structure safety assessment are recently receiving a lot of attention. Acoustoelastic Effect is the material mechanical property, therefore, to apply velocity of elastic wave to structure stress condition assessment, stress-elastic wave relationship of structure materials should be known. Accordingly, the study of stress-elastic wave velocity relationship of structure materials is conducted very much, and a lot of studies to investigate the stress-elastic wave relationship of concrete which is one of construction typical materials are conducted so actively. Not like the homogenous material such as structural steel, the velocity of elastic wave of concrete is can by changed not only by the stress condition but also by the others` material and mechanical properties. Therefore, in order to investigate the relationship of stress-elastic wave velocity relationship, the study of this property`s influence on stress-elastic wave velocity is required. For this reason, in this study, the influence of stress-elastic wave velocity on properties of mix and strength of concrete is analyzed. For this, loading test and elastic wave propagation experiment is conducted making concrete specimens with different mix proportion, and hereafter, the influence of mix proportion of concrete on stress-elastic wave velocity relationship is analyzed. Meanwhile, for concrete has lower sensitivity of elastic wave velocity to stress, in case of using existing elastic wave velocity measurement method, it is hard to measure the elastic velocity changes by stress changes precisely. Coda Wave Interferomety Technique is a developed signal processing technique in the field of seismology, and based on the cross correlation function about the estimated seismic wave, this technique is a method to measure the fine temporal variation of the seismic wave accurately. In this study, to analyze the relationship of stress-elastic wave velocity by concrete mix proportion accurately, elastic wave changes is found using Coda Wave Interferometry Technique.